Battery Charger Amps

[tundrawolf]

I was using just a dead short, just the ammeter.

I was thinking, if it's only 1.9A, then a battery would be necessary. However, I don't want the batter charging all the time, because of the drag it adds to the already small 110cc engine. Is there a way around this?

 

[MikeMl]

I have gone over the Circuit diagram I thing on the previous Circuit diagram that I drew I have the E, B, C 2N3906 the wrong way around but the one that I have attached to this post is correct Could you advise me if the E,B,C is correct.
I have made the board and I have placed the components on the board.
Just going through the final check.
Will place a photo of the finished project as soon as I am convinced that every thing is ok.

Yes, the emitter of the 2n3906 is tied to the 14V bus.

 

[MikeMl]

I was using just a dead short, just the ammeter.

I was thinking, if it's only 1.9A, then a battery would be necessary. However, I don't want the batter charging all the time, because of the drag it adds to the already small 110cc engine. Is there a way around this?

Ok, this may be a case where a SERIES Regulator may be preferable over a SHUNT regulator.

The advantage of a series reg is that once the battery is charged, the current drawn from the alternator stator winding will become essentially zero, so no it takes no torque away from the rotating flywheel. OTOH, since the maximum current you will be drawing will be ~2A, and 2A@14V is 28W, and 28W is 28/746 HP = 0.037HP, I think that the engine will hardly notice it.

The problem of using a series regulator is that the regulator element (IC/Transistor/FET) will have to withstand the open-circuit voltage that comes out of the alternator stator at max RPM/zero load, which precludes using a simple LM317, etc.

 

[tundrawolf]

Thank you, Mike you have been a great help. I have been looking on Ebay for regulator/rectifiers, there are many inexpensive ones for motorcycles, however, the problem is that I have no idea what the internal circuitry is like. Is there per chance a series regulator rectifier schematic?

Hey, here's something interesting. I thought about what you said about motor drag-and guess what-you are right. Not even at such a low idle that the engine is about to die does grounding out the stator output have any effect on engine load.

Here's another interesting thing. A thought came to my mind, I have lots of electronic components. I tried connecting the small inflator to the wire directly, the motor only vibrated.

Here's what happened when I tried different rectifiers I had.

A single large diode, MBR7545 T8616: Inflator turns, but not fast enough to generate any compressed air.

3 pin Rectifier MPIRC40?10 8530: Turns over faster, actually. Connections are AC/AC/+. Still, not enough to generate significant compressed air.

4 pin rectifier MDA970A6 8506: Turns over MUCH faster! Like to a battery almost. Generates 30 PSI. However rectifier gets hot to the touch after just a few seconds.

4 pin rectifier KBPC3506W 28 22954234A: Spins over as fast as previous rectifier. 30 PSI generated. Barely warm to the touch, larger rectifier.

4 pin rectifier KBPC10-06: Large metal cased unit. 30 PSI. Barely warm to the touch.

Now, why did the motor spin so fast when connected to the rectifiers with 4 pins as opposed to 3, or the single diode?

 

[tundrawolf]

Here's something ironic. While I am trying to figure out a rectifier for my ATC, my motorcycle, which is my only mode of transportation, seems to have a failing rectifier/regulator.

 

[tundrawolf]

So I have the "old" rectifier/regulator. When they go bad, they cook the battery (Too much voltage). It is a 3 phase rectifier. It has a negative, a positive output, and 3 inputs for phase. How do I wire this thing so that it works with a single phase system? Do I connect all 3 phase inputs together, and then to the single phase output? Or just use one leg? I'd rather make use of the entire thing, I may try connecting all 3 legs together. But I am not sure if this is wise. Anny suggestions?

 

[MikeMl]

A three-phase alternator takes a six-diode full-wave bridge rectifier similar to what an automotive alternator has in it. I think you should dig into your single phase winding to see if you cant unground the winding and bring out both ends of the winding. That would enable you to use a full-wave four diode bridge, and get twice as much power out of the winding.

 

[tundrawolf]

I don't understand. How is having the other end free of the chassis ground different than tapping into any point on the chassis ground? Do you mean center tapping the coil?

I want to use the old 3 phase rectifier from my bike (That may be overcharging) on the ATC 110.

 

[MikeMl]

No center tap required. You just need access to both ends of the stator winding. You said there is only one wire coming out of the flywheel area of your motor, which means the other wire must be grounded. If you can un-ground it and bring out two wires (both ends of the winding, so the winding is floating with respect to ground), then you can connect the two wires to the AC terminals of a single-phase full-wave bridge rectifier and have twice the effective current with much less ripple.

 

[tundrawolf]

So, grounding effectively saps half of the current? Wow. I am not sure if it is in an oil bath or if it has a dry magneto. I may attempt that.

 

[MikeMl]

Here is a sim showing a comparison between running with a stator one end of which is grounded (allowing only half-wave rectification) vs a floating stator (allowing full-wave rectification).

The load is the same. Look at the voltage across the load.

 

[tundrawolf]

The voltage for the grounded side is slightly higher? Does that mean there is less current?

 

[MikeMl]

The voltage for the grounded side is slightly higher? Does that mean there is less current?

That is a consequence of having two forward diode voltage drops in series in the full-wave bridge vs only one in the half wave. However, the power delivered by the FW circuit is 4.2W while that delivered by the HW circuit is 2.4W.

 

[tundrawolf]

That's amazing. Is there a reason? Does the chassis act like a sort of ionic dissipater? You know what I mean?

 

[tundrawolf]

Is the 3 phase regulator useless for this project?

 

[MikeMl]

You have confused me. You started this thread saying that your stator winding is single phase, and one end is grounded. Now you say that you have a three phase stator and a three phase rectifier/regulator. Which is it???

 

[tundrawolf]

I apologize, I thought it was clear, I do have a single phase alternator, however on my motorcycle (I only have a motorcycle as transportation, the vehicle with the single-phase alternator is an offroad ATC) which has a 3 phase alternator, the rectifier is in the middle of going out. I was asking, if it would be possible to use the 3 phase regulator from my motorcycle for the single phase alternator on the ATC.

 

[tundrawolf]

The reason I ask is because I am contemplating heating it up a little bit, and digging out the soft almost silicone-like glue that covers the components, and trying to repair it. But I could damage it in the process, so I would only like to attempt it if it is not useful for the ATC.

I might just take this regulator rectifier apart and try to diagnose it. I wonder if a hot knife would work well for cutting out the glue.

 

[Gregory]

I have made my circuit board installed all components and heat sink's Applied AC voltage from my variac and increased the AC voltage and had a multimeter on the AC side and the DC side across a 60 W bulb ( load )
The AC voltage input only got to 20Volts AC and the DC volts 12.4 Volts Dc at the load.
The IRFZ24N was getting very hot where I could only touch the Fet. and the 0ne Ohm 50W got hotter.
I could not go any higher as smoke started to come out of the Variac,
The Trim pot only adjusted the volts to up and down 4Volts DC.
Can I use a variac to test this project.
If so what has gone wrong .
I can post a photo of the board and components If required.
Help

 

[MikeMl]

Everything is working as designed. The reason things are getting hot is because a VARIAC is a voltage source; while an alternator is a current source; you are subjecting the regulator to unusually high currents which will NOT happen if you connect the regulator across the output of the alternator. Circuit is fine, the testing set-up is not.

To simulate the current-limited nature of your alternator, put a 25W 120V or 240V incandescent lamp in series with the line input to the variac. That will limit its maximum output current to something like the alternator can supply. This should allow you to turn up the variac where its open circuit output voltage matches the open circuit voltage output from your alternator.

When then connected to the regulator, it will pull down the voltage to the voltage limit established by the shunt regulator. The shunt regulator, by definition can only work if the source connected to it has a finite output resistance, which your "naked" variac does not! Putting the lamp in the Variac input will simulate the required source resistance.

To set the final regulated voltage, the battery must be in the circuit. Set the voltage across the battery terminals to 14.5V